Identifying a JIS headset

Todd Bryan said:

Greetings to all. The original headset on my circa 1979
Miyata "Seven Ten" frame is indexed and I want to replace
it. I don't know if this headset is ISO or JIS, and I'd
rather avoid pulling the fork and races to measure it. Are
there other telltale identifying signs to look for? The
headset is unmarked, but it does have an odd 33 mm
lockring.

That is almost certainly J.I.S.

Sheldon "Educated Guess" Brown +------------------------------------------
+
| So we'll go no more a roving |
| So late into the night, |
| Though the heart be still as loving, |
| And the moon be still as bright. |
| |
| For the sword outwears its sheath, |
| And the soul wears out the breast, |
| And the heart must pause to breathe, |
| And Love itself have rest. |
| |
| Though the night was made for loving, | And the day
| returns too soon, | Yet we'll go no more a roving | By
| the light of the moon. | --Lord Byron |
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Todd Bryan said:

Greetings to all. The original headset on my circa 1979
Miyata "Seven Ten" frame is indexed and I want to replace
it. I don't know if this headset is ISO or JIS, and I'd
rather avoid pulling the fork and races to measure it. Are
there other telltale identifying signs to look for? The
headset is unmarked, but it does have an odd 33 mm
lockring.

The original in that bike is JIS

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971